Worth reporting minor bumps?

[Belmit]

On my way home in a queue of traffic this evening someone tapped my rear bumper. As far as I remember I was probably coasting at very low speed myself rather than stationary so some of the impact would have been lessened as well. I whacked on the hazards, jumped out and asked the guy to pull up in a layby I knew. Nice guy, American I think (judging only on accent).

We took a look and there was no visible damage, not even a scuff. I still need to check the light in the bumper but as far as I was concerned I was happy to swap details (got them off his licence) and head off. Need to take a look in the daylight but I'm 99% sure that nothing is wrong, and I have no desire to make anything more of it if that's the case. I just wanted to know if it's worth letting my insurance company know it happened.